1. Mystery Men - Brilliant comedy, it's a shame it came out right before the big Superhero movie boom. I keep thinking "if only it'd come out 5 years later, it would have been a huge hit." It deserves a sequel IMO.
2. X-Men: The Last Stand - Seriously, every time I hear fanboys whine about this movie, I want to karate chop them. Brett Ratner and crew did an excellent job finishing what was started with the first two X-Men movies and threw in plenty of fanservice, and was still mauled by rabid fanboys. Shame. At least it did well at the BO.
3. TMNT - Less than 100 million at the box office? Preposterous! This was an excellently made movie, and the animation was close to Pixar quality at times. I seriously don't know what kept it from being a success. Maybe it was the close proximity to the kids' TV show (which was falling off the radar by the time TMNT came out), or maybe it was the release date (Christmas and pre-summer, and mid-summer are the big movie seasons, not late winter!), but whatever the case, the movie did not get noticed by moviegoers. It almost makes me want to cry.
4. Hulk - It was a little too psychological and not quite fun enough IMO, but it was still excellently acted and had a brilliant cast. It's a shame that the sequel will be pretty much entirely recast, because that was one of the biggest strengths of Ang Lee's offering. It seemed almost like a re-visit of the classic Universal monster movie heyday, but for the 21st century. I liked it a lot, and I wish that it had been more accessible so that more people would have been inclined to see it.